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Cooling for Distillation 
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#1
Nov513, 12:29 PM

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Hi,
I am new to the forum and would like your thoughts and idea on a project I am currently working on as a chemical engineering student. I have to design a cooling system for a distillation column using water pumped from a pond nearby. I have been given the distance to pump this water and told that the heat generated by column (Q). We are also told that in heat transfer Q=V*p*C*DeltaT where V = volumetric flow rate, p=density, C=specific capacity. I am currently having some problems choosing the right pump. I have to optimize the volumetric flow rate and pipe diameter in order to decide the exiting temperature of the flow stream. I am lost on how to optimize the various parameters in order to choose the optimum pump. My question is how do you go about optimizing the pipe diameter, volumetric flow rate and even things like pressure drop, shaft work of the pump all come in. Any help would be greatly appreciated, thanks 


#2
Nov513, 04:22 PM

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P: 11,925

Optimize with which target? A larger pipe will lead to a lower pressure drop at the same flow rate. It is just harder to fit in.
Based on the known Q, you can relate the exit temperature to the volumetric flow rate. And this can be related to pressure drop. 


#3
Nov513, 04:56 PM

P: 2

Thanks for the reply,
I am given the opportunity to manipulate the pipe diameter, shaft work of the pump, volumetric flow rate and the exiting temperature of the flow rate. The target is make the shaft work little. The issue I am having what value should I start manipulating. You said I should start with the exit temperature but how do I decide what the exit temperature should be? 


#4
Nov613, 08:03 AM

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P: 11,925

Cooling for Distillation
Well, you can find the relations I posted, and shaft work should be related to pressure difference and volumetric flow rate. Beyond that, I have no idea. I don't think there is a ideal minimum for shaft work, just practical limits (like the size of the whole setup, or friction in real pumps and so on).



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